1. Field of the Invention
The present invention relates to a method of transplanting hematopoietic system reconstituting cells between genetically unrelated individuals using a combination of treated mononuclear cells and bone marrow or peripheral blood hematopoietic system reconstituting cells.
2. Background Art
Allogeneic bone marrow transplantation is the preferred treatment for a variety of malignant and genetic diseases of the blood and blood-forming cells. The widespread application of this therapy is limited by the availability of suitable bone marrow donors who are genetically related to the patient and share the same transplantation antigens on the surface of their blood cells. Only 25% of patients have a sibling who is an antigenically matched potential donor. Bone marrow transplantation can be offered to those patients who lack an appropriate sibling donor by using bone marrow from antigenically matched, genetically unrelated donors (identified through a national registry), or by using bone marrow from a genetically related sibling or parent whose transplantation antigens differ by one to three of six human leukocyte antigens from those of the patient. However, using antigenically mismatched, genetically related parent or sibling or antigenically matched, genetically unrelated donors, the likelihood of fatal graft vs. host disease (GvHD) and/or graft rejection increases from 20% for matched sibling donors to 50% in the cases of matched, unrelated donors and un-matched donors from the patient's family. Further, in cases where an unrelated donor is not matched at one of the six major transplantation antigens, graft rejection and/or fatal GvHD increases to 60%.
GvHD is a disease with significant morbidity. Patients who develop acute GvHD may develop blisters covering most of their skin surface, massive gastrointestinal bleeding or fulminant liver failure and jaundice. Patients who develop chronic GvHD may develop scleroderma that results in joint contractures and skin ulcers, hair loss and a generalized wasting syndrome. Patients with acute or chronic GvHD are immuno-suppressed and at risk for life-threatening opportunistic infections similar to those that develop among AIDS patients.
The removal of T cells from the bone marrow obtained from matched unrelated or unmatched sibling donors results in a decreased incidence of graft vs. host reactions, but an increased incidence of rejection of the allogeneic bone marrow graft by the patient. Thus, lymphocytes, and especially T cells, present in the allogeneic bone marrow graft are important to ensure engraftment in antigenically and genetically mis-matched recipients. T cells present in the allogeneic graft also have an important role in eliminating residual cancer cells in the recipient, a phenomenon termed "graft vs. leukemia effect." The "ideal" donor T cell in an allogeneic bone marrow or stem cell graft would have the ability to prevent graft rejection and mediate the graft vs. leukemia effect without producing GvHD. The potential to successfully transplant T cell-depleted, or stem cell-enriched bone marrow or stem cells from antigenically mis-matched donors to patients without graft rejection or GvHD would greatly extend the availability of bone marrow transplantation to those patients without an antigenically matched sibling donor.
In a dog model of allogeneic bone marrow transplantation, the addition of viable donor lymphocytes to the bone marrow graft resulted in an increased frequency of stable engraftment, from 9% using antigenically mismatched bone marrow alone, to 88%, using a combination of bone marrow and donor lymphocytes. However, all the animals that received donor lymphocytes died of lethal GvHD (Storb et al (1968) "Marrow grafts by combined marrow and leucocyte infusions in unrelated dogs selected by histocompatibility typing" Transplantation 6:587-593).
An alternative to infusions of viable donor lymphocytes has been the use of irradiated donor lymphocytic infusions in the post-transplant period. The addition of donor lymphocytes that had been previously irradiated to a dose of 20 Gy (2,000 rads) to allogeneic bone marrow cells did not prevent fatal graft failure when the mixture was administered to lethally irradiated dogs antigenically mismatched for dog leukocyte antigens (DLA), (Deeg et al (1979) "Abrogation of resistance to and enhancement of DLA-nonidentical unrelated marrow grafts in lethally irradiated dogs by thoracic duct lymphocytes", Blood 53:552-587).
In genetically unrelated rabbits, a series of five infusions of donor lymphocytes, irradiated to 15 Gy (1,500 rads) one to ten days following the infusion of allogeneic bone marrow cells and irradiated autologous bone marrow cells decreased the rate of graft rejection from 60% to 20%, but only 30% of the treated animals survived more than 100 days with donor derived hematopoietic cells and 40% of animals that received T cell depleted bone marrow followed by irradiated allogenic lymphocytes developed GvHD. (Gratwohl et al. (1987) "Engraftment of T-cell depleted rabbit bone marrow" Acta haematol. 77:208-214).
The addition of antigenically matched viable donor lymphocytes obtained from the bone marrow donor and given 1-5 days post-transplant to 43 patients undergoing allogeneic bone marrow transplantation for aplastic anemia resulted in a 14% incidence of graft failure compared to 22% in a similar group of 20 patients who received the bone marrow transplant without additional donor lymphocytes. However, the incidence of acute GvHD was 36% in the group treated with donor lymphocytes compared to a 20% incidence of acute GvHD in the group that received bone marrow cells alone. In both groups, 20% of patients ultimately died of GvHD, (Storb et al (1982) "Marrow transplantation with or without donor buffy coat cells for 65 transfused aplastic anemia patients", Blood 59:236-246).
In a clinical report describing the use of irradiated human lymphocytes, 20 patients with hematological malignancies were treated with high-dose chemotherapy and total body irradiation followed by the infusion of T cell-depleted antigenically matched, genetically related allogeneic bone marrow cells. One, three, five, seven and fourteen days following bone marrow transplantation, the patients received infusions of donor lymphocytes, irradiated to 15 Gy (1,500 rads). The authors reported no cases of graft failure, but noted an overall incidence of GvHD of 85% and a 15% incidence of fatal GvHD, (Gratwohl et al. (1988) "Irradiated donor buffy coat following T cell-depleted bone marrow transplants", Bone marrow transplantation 3:577-582).
These reports suggest that infusions of irradiated donor lymphocytes are not toxic to recipients of bone marrow transplantation, but do not demonstrate clear efficacy in either preventing graft rejection or GvHD. The present invention overcomes the problems in the art by providing a method of transplanting hematopoietic system reconstituting cells from a donor to an antigenically matched or unmatched, genetically unrelated recipient or an antigenically unmatched, genetically related recipient with successful engraftment in the absence of GvHD.